Preface: I am not an expert at plastic pouring/mixing/etc

Hack method for bait repair is as follows...

Take some old plastic baits, preferably clear or clear with silver flake. Do not use baits that are salt impregnated. Big Hammers work good for doing this. Any of Rago's plastic baits work good too. Chop the baits up into small pieces and put them in a small pyrex cup.

Put that in the microwave for 2 minutes. Watch the plastic the entire time. You'll see it melt down and turn to liquid. Give it maybe 15-30 seconds after it liquifies before you stop the microwave. If you see it start to smoke or scorch, stop immediately.

Use a hot mitt, grab the cup and stir the plastic with a wooden stick or whatever you have handy. Stir it quickly and immediately pour some into the hole in your bait. Sometimes I cut away the torn plastic around where the hook goes in so its a cleaner pour. It also helps if you prop the bait up between two objects so that you can pour immediately and not risk pouring it on your hand. It only takes a little bit of plastic so pour it slowly and just try to make a little raised bump of plastic on the spot but remember, the hotter the plastic is the better it will bond to the bait. If you pour the plastic when its kinda gooey it won't stick to the lure as well. The plastic will probably drip down the side of the bait so just do what you can to control it. It'll dry pretty fast. Typically I make a mess every time I do it, but it does work and will make your baits last longer.